Means for broaching surfaces



I A. L. NILSSON 2,150,455

MEANS FOR BROACHING SURFACES I Filed June 30, 1934 3 Sheets-Sheet 1 4/ 4INVENTOR.

fixeZ Z. A/z'lssofi.

A TTORNEYS.

March 14, 1939. A L, NILSSQN 2,150,455

MEANS FOR BROACHING SURFACES 5 sheet-sheet 2 Filed June 30, 1934 4,5MWRS 4/ Z 3/ E4 X w M" m 1.3

9 1 INVENTOR.

I fixer! A. Nzllason.

ATTORNEYS.

March 14-, 1939. v A INILSSQN 2,150,455.

MEANS FOR BROACHING SURFACES Fiied June 30, 1934 3 Sheets-Sheet 3INVENTOR. flare-l 4. Ni 1 s5 0 n.

A TTORNEYS Patented Mar. 14, 1939" UNITED STATES PATENT ()FFiCE Axel L.Nil'sson, Pleasant Ridge, Mich.,. assig'nor't'o: Colonial BreachCompany, a; corporation of Michigan Application June 30 1934, Serial No.733,184

3 Claims.

My invention relates to methods and means for breaching surfaces andparticularly to a method and means for breaching flat surfaces byprogressively machining from the side edges 5 of such surfaces.

Heretofore, when breaching flat surfaces, broad breaching tools wereemployed which were drawn over the surface to plane the surface todesired dimensions. While in certain instances this method of breachingproved satisfactory, on certain materials suchlas castings having hardsurfaces, this method proved impractical.

In practicing the present method, hard surfaces of casting or other hardmaterial may be broached by having the cutting occur progressively fromthe edge inwardly across the face of the element to be surfaced, duringthe longitudinal movement of the breach. To effect such operation, thebreach is set at an angle to its direction of movement to have theopposite ends of the breach extend across the face of the work piece. Inthis manner, the leading teeth will start cutting at one edge of thework piece and cutting will progressively occur across the surface asthe broach is moved longitudinally. The hard surface is not directlyattacked by the teeth of the breach, since the material will crumbleaway as the teeth progressively advance from the side edge across thetop surface.

When the surface is wide, two breaches, convergingly disposed relativeto the direction of movement of the breach, may be employed facing eachother and spaced at one end sufficiently to span the work so as tomachine progressively during the longitudinal movement of the breach.

A scraping section may be provided on the tool following the breachingteeth to plane the rough edges produced by the teeth on the surface ofthe work piece when an extremely smooth surface is desired.

The broaching bar may be adjustably mounted on the tool so that theangleof the teeth relative to the work may be changed. In this manner thedepth of the cut may be regulated to correspond to the types of materialto be machined. The broach may be of the built-up type having aplurality of blades which are bolted or otherwise secured together anddisposed in predetermined relation to each other. The built up breachingbar may likewise be swung to be disposed at various angles to the work.The

blades of the built-up broach may be readily sharpened and renewed.

5 Various spacing and depthof groove between from opposite edgesinwardly toward each other the teeth may be provided to correspond tothe different materia1 upon which the teeth are to operate. When thebreach is operated on cast iron or the like, teeth may be provided onthe bottom and side of the breach so that the chips may pass upwardly oracross the bottom of the breach free of the work. The teeth may beomitted from the bottom face when employed on more ductile material toforce the chips to move upwardly so as not to clog the breach as wouldoccur if they should catch on the corner between the two sets of teeth.Further, the corner could be rounded to prevent such catching of thechips to force them to flow in either one or the other direction.

Accordingly, the main objects of my invention, are; to set a breachingbar angularly to the direction of movement of the breaching tool toeffect the progressive machining of the surface of a work piece from theside edge across the face thereof; to relieve the teeth of an angularlydisposed broach at an angle greater than the angle at which the breachis set relative to its direction of movement to provide a relief to theteeth relative to the work; to provide a plurality of breaching barsdisposed in spaced converging relation to each other to be capable ofprogressively machining a surface from opposite edges of the workelement; to provide a breaching bar which is adjustable angularly of thedirection of movement of the breaching tool to present a different angleof attack to the material of the surface of an element across which-thebroach is drawn; to provide a breaching tool of the built-up type withaplurality of blades mounted in spaced relation to each other with aproper relief to the cutting edges when the breaching tool is disposedat an angle to its direction of movement; to provide a breaching toolwith breaching bars one of which cuts a groove while the outer barsmachine the surface ef the block progressively from available edgesacross the face thereof; and, in general, to provide a breaching toolcapable of machining the surface of a work piece from the availableedges thereof which is simple in construction, economical of manufactureand positive in operation.

Other objects and features of novelty of my invention will be eitherspecifically pointed out or will become apparent when referring, for abetter understanding of my invention, to the following description takenin conjunction with the accompanying drawings, wherein:'

Figural is a broken view, in elevation, of a broaching machine embodyingfeatures of my invention,

Fig. 2 is an enlarged sectional view of the structure illustrated inFig. 1, taken on the line 2-2 thereof,

Fig. 3 is an enlarged sectional View of the structure of Fig. 1, takenon the line 3-3 thereof,

Fig. 4 is a bottom plan view of the broaching tool illustrated in Fig.3,

Fig. 5 is a view of the broaching tool illustrated in Fig. 4, taken onthe line 55 thereof,

Fig. 6 is an enlarged sectional view of the structure illustrated inFig. 1, taken on the line 6-6 thereof,

Fig. '7 is a broken View of structure similar to that illustrated inFig. 4, showing a modified form thereof,

Fig. 8 is a view, in elevation, of the structure illustrated in Fig. '7,

Fig. 9 is a broken view of structure similar to that illustrated in Fig.4, showing a further form thereof,

Fig. 1.0 is a view, in elevation, of the structure illustrated in Fig.9,

Fig. 11 is a view of a section of the broach,

imilar to that illustrated in Fig. 6, showing a modified form thereof,

Fig. 12 is' a bottom plan view of a broach, similar to that illustratedin Fig. 3, showing a modified form thereof,

Fig. 13 is a left end view of the broach as illustrated in Fig. 12,

Fig. 14 is a view of a broach, similar to that illustrated in Fig. 12,showing a further form thereof,

Fig. 15 is a bottom plan View of a broach, similar to that illustratedin Fig. 3, showing a further form thereof, a

Fig. 16 is an enlarged broken View of the broach illustrated in Fig. 15,

Fig. 17 is a side view, partly in section, of the broach illustrated inFig. 16 taken on the line lI-l'! thereof, and

Fig. 18 is a sectional view of the structure illustrated in Fig. 16,taken on; the line I8-I8 thereof.

In Fig. 1, I have illustrated a broaching machine 20 having a'work piece2! clamped thereon by suitable clamping means 23. The work piece may beof any shape having a surface which is to be planed by the broachingtool 28 during the machining operation. The planing operation iseffected through the progressive advance movement of the broachingteethlaterally across the surface as the broaching tool is pulledthereacross. This is effected through the angular position of thebroaching bar relative to the work. The hard scale present on thesurface of a casting, for example, will be progressively cut and removedis not directly attacked by the broaching teeth as heretofore attemptedwhen the broaching teeth were directly forced into the surface of thework piece.

A head 24 is supported on ways 25 to be adjusted vertically by a screw26 to regulate the position of the broaching tool relative to the work.Ways 2'! are provided on the head 24 which support the broaching tool 28for movement longitudinally of the machine. Movement is effected by thepull rod 29 which is attached to the broaching tool 23 by a coupling 3!.The rod 29 is connected to a hydraulic cylinder 32 to be manipulated inthe usual manner.

- The broaching tool 28, as illustrated in Figs. 2

and 3, includes a base 33 having extending arms 34 which are supportedin the ways 2? by plates 35. The base is guided by a land 36 extendingin a groove 31 on the top face of the plate. The bottom surface of theplate supports a broaching bar 38 having a plurality of teeth on itsbottom and side. The broach bar is supported diagonally across the base33 and is braced by a backing element 39.

The teeth 41 of the bar 38 are sloped at 42 at such an angle as toprovide the proper degrees of relief to the cutting edges relative tothe work. In View of the angular disposition of the broaching bar, theslope 42 must be materially increased over that heretofore employed andmust be equal to the angle of the bar plus the degree of relief requiredfor the cutting operation. Suitable screws 43 are employed for clampingthe broach bar 38 to the base 33 and the backing element 39 thereon andto the broach bar.

As the rod 29 is drawn into the cylinder 32, the base 33 of the broachis drawn along therewith to have the teeth 4! progressively machine thetop side of the work element 2|. The teeth 4| are disposed to intersectthe entire surface of the element 2| so that the machining operationprogressively advances across the surface from one edge, as illustratedin Fig. 2. At the end of the longitudinal movement of the broach base33, the teeth 4| will have machined entirely across the top face of thework element to produce a true, accurate surface thereon.

The chips from the cutting operation will readily flow in the grooves 44between the teeth, both across the bottom and upwardly of the broachingbar 38 to prevent the clogging of the teeth. W ile teeth of this formhave proved satisfactory for machining cast iron or other materialswhich readily crumble, difficulty-has been experienced on more ductilematerials when the chips do not readily break up. Such chips catch onthe corners between the grooves and fail to move in either direction.The piling up of the chips loads the machine and causes damage to thebroach and to the work piece.

In Figs. '7 and 8, I. have illustrated a broaching bar 45 which issimilar to the bar 38 with the exception that the teeth 46 on the bottomface of the bar have only a slight groove 44 therebetween to prevent anyof the chips from moving therein and to cause them to move directlyupwardly along the large openings 44 provided between the side teeth Mwhich effect the cutting operation. The teeth 46 aid the operation byplaning a smooth surface on the. work piece.

In Figs. 9 and 10, I have shown a further form of broaching bar 41 whichis similar to the bars 38 and 45 with the exception that the bottomteeth are entirely omitted and the side teeth 4| alone are employed forthe machine operation. In Fig. 11, I have shown a modified form ofbroaching bar 38 wherein the corners at the intersection of the grooves44 are rounded off at 48 to prevent the chips from catching and therebyto be forced either laterally or vertically in the groove away from thecutting edges of the teeth. When any of the above-mentioned types ofbroaching bars are employed, the progressive movement of the teethacross the top surface of the work element is effected during thelongitudinal movement of the broach, caused by the angular dispositionof the broaching bar relative to the work element.

This method not only decreases thetime required for a broachingOperation, but materially lengthens the life of the broaching bar andreduces the cost over a scraping type of broach which was attemptedheretofore to be pulled directly across the surfaceof the work piece. Itmay readily be seen that when a hard cast iron surface is to be attackedby a scraping broach,

the roughing teeth would be immediately ruined when attempting to outdirectly into hard surface of the cast material. In the presentconstruction this damage to the teeth is entirely eliminated in view ofthe side approach of the teeth across the surface and the breaking up ofthe hard cast surface during the progressiveadvance of the teeth acrossthe face.

In Figs. 12 and 13, I have shown a further form of my invention whereina broaching bar is constructed to machine the entire crank case surfaceof an engine block. In this operation not only is the surface of theblock machined, but at the same time the bearing grooves are likewisemachined in the casting. The machining is effected in the same manner bybars having teeth which progressively advance across-the face of thework to machine its surface from the side edge progressively across theface as the broach is pulled longitudinally across the work. The base 33of the broach has a pair of broaching bars 38 mounted thereon in amanner similar to that above specified relative to the constructionillustrated in Fig. 3 with the'exception thatthe cutting edges facetoward eachother and the bars are converging with the open ends ofsufficient width to engage the outer surface of the work, in thisinstance the engine block 49.

A round broach 5| of conventional design may be disposed centrally ofthe bro-aching bars 38 for the purpose of machining a bearing groove 52in the block. At the rear end of the broaching base 33, scraping plates53 may be employed on either side of the finishing end 54 of the bearinggroove broach 5| for the purpose of scraping the top surface of theblock after the machining operation to eliminate the teeth markstherefrom and to provide a perfectly smooth finish to the surface.

During the pulling of the broach by the pull bar 29 through theconnection 3!, the broaching bars 38 machine from opposite sides of theblock inwardly toward the center, machining the surface thereof in thesame manner as the surface of the element 2! was machined, with theexception that the machining occurs from both edges toward the center.During this machining operation the bearing grooves are likewisemachined and near the end of the machining operation, a final planing ofthe surface may be effected by the scraping blocks 53, while a finishingoperation will be effected on the bearing grooves by the finishingportion 54 of the broach 5|.

In Fig. 14, I have shown a further construction of my invention whereinpairs of bars 38 are employed. This is made possible by the interruptionof the surface at the center of the block by the bearing groove 52 whichmay be roughed cast therein.

In this construction each half of the bearin block is machined by thepairs of broaching bars 38 which are disposed on each side of thecentral bearing groove broach 5|, which is shortened and disposed asillustrated in the figure. The central adjacent ends 50 of the pairs ofbroaching bars 38 enter the groove 52 to machine outwardly therefromwhile the outer broaching bars 38 machine inwardly from the edges as thebroach is drawn across the block. The broach may be materially shortenedin view of the fact that only half of the surface of the block ismachined by each pair of broaching bars during the pull operation. Thescraping blocks 53 may be employed in' rear of the pairs of broachingbars 38 as in the structure of Figs. 12 and 13 for effecting a finalfinish to the surface.

It will thus be seen that the broach may be constructed in any. manner,depending upon the shape of the work piece and the number of edges wherethe broaching bars may enter to effect a side machining operation. Whena large surface is divided by several grooves passing therethrough thebroach may be shortened by employing breaching bars at each groove to beoppositely disposed to machine outwardly therefrom while others aremachining from the opposite direction inwardly toward the grooves. Theshape and construction of the broach may change in accordance with theshape and contour of the work element having a surface to be machined.

In Figs. 15 to 18, I have shown a further form of broach, one that ismore universal in operation, which may be adjusted at various angles toregulate the amount of depth the teeth will cut. The further novelty ofthe broach resides in its builtup teeth which may be readily removedand.

sharpenedand adjusted in any manner relative to its support. The broachbase 33 has a backing bar 55 thereon having a plurality of adjustingscrews 56. The broaching bar 5! is of the builtuptype and is pivoted atthe rear end on the pivot 5B while the opposite end is provided with anarm. 59 having a slot 6| through which a clamping bolt 62 projects. Thebroach 5'! may be adjusted to any angle relative to the base 33 and maybe clamped by the bolts 56 and 62 against movement. This angularadjustment of the broach regulates the amount of surface which will bemachined and at the same time regulates the depth of cut effected byeach tooth. It is to be understood that with different materials. adifferent amount of machining may be effected by the teeth. Cast iron,for example, is susceptible to a greater depth of out than a steelalloy. while the same will be true of a bearing metal or a bronze.

The broaching bar 51 is illustrated enlarged in Figs. 17 and 18 andcomprises a plurality of blades 63 spaced by a plurality of blocks 64whichare secured in a holder 65 by suitable bolts 66. A

threaded rod 61 extends through the blades 63 and the blocks 64 forsecuring them in clamped relation. The relief 42 provided on the teethis sufficient to provide the desired clearance when the broach isdisposed at its greatest angle, so that free machining will always beeffected by the teeth during themachining operation.

While I have illustrated a particular construction of blades, spacingelements and means for securing them together and in a holder, it'is tobe understood that other forms of blades and elements may be providedsuch as wedges, channel elements and the like, it being understood thatthe construction shown is employed primarily for the purpose ofillustration. When a sharpening operation is to be effected on theteeth, the blades may be removed and faced on a suitable machine andreassembled in the holder as shown.

The various broaches herein described'and illustrated are constructedfor the particular purpose of facing a work element by having the teethprogressively machine across the face from a side edge during the timethe broach is pulled longitudinally. This is effected by having thebroaching bar disposed at an angle with its ends rojecting beyond thewidth of the surface to be machined. An angle is provided to the cuttingedges such that the desired relief will be present between the teeth andthematerial of the work .element irrespective of the angularity of thebroaching bar relative to its direction of movement. When it is desiredto eliminate all teeth marks from the surface machined by the broachingbar a scraping portion may be provided rearwardly of the broach to dresssuch marks from the surface during the final movement of the broachthereacross. The actual machining, however, is effected through theprogressive cutting by the teeth from the side edges across the surfacebeing machined.

While I have described and illustrated several embodiments of myinvention, it will be apparent to those skilled in the art that variouschanges, omissions, additions and substitutions may be made thereinwithout departing from the spirit and scope of my invention, as setforth in the accompanying claims.

I claim as my invention:

1. The combination with a breaching machine,

of means for supporting a work piece to be surfaced, broaching barsconvergingly disposed tohave the inner sides facing each other, teeth oneach of said inner sides, the spaced ends of said bars being of a widthto receive opposite side edges of said work piece, the adjacent ends ofsaid bars disposed to machine the central portion of said work element,and means for pulling said broaching bars across the Work element tohave the teeth thereof progressively cut inward- 1y from side edges tomachine the top surface during the longitudinalmovement of the breach.

2. Thecombination with a broachingmachine, of means for supporting awork piece to be surfaced, breaching bars convergingly disposed to havethe inner sides facing each other, teeth on each of said inner sides,the spaced ends of said bars being of a width 'toreceive opposite sideedges of said Work piece, the adjacent ends of said bars disposed tomachine the central portion of said work element, means for pulling saidbroaching bars across the work element to have the teeth thereofprogressively cut inwardly from the side edges to machine the surfaceduring the longitudinal movement of the broach, and a scraping blockprovided rearwardly of said broaching bars for dressing the teeth marksfrom the surface machined.

3. A broaching machine for finishing the surface on a work elementincluding, in combination, a pair of angularly disposed broaching barsconvergingly disposed to have the inner sides facing each other, teethon each of said inner sides, the ends of said bars being spaced toengage opposite sides of the work element, a broach disposedtherebetween'for machining a groove interjacent the edges of saidsurface, means for securing said broaches in unit fixed relation, andmeans for drawing said broaches across the surface to have the teethprogressively cut inwardly from the outer edges and to machine thegroove during the longitudinal movement.

AXEL 'L. NILSSQN.

